Upper circle diameter: 8CM; Inner circle diameter: 4CM, so please pay attention that the screw tip cannot exceed 4CM. Set details: 4 pressure screws; length 8cm/3.15in. M10 screws. White. They are ideal for child safety gates, pet gates, etc. It will prevent your children or pets from leaving the safety area. Material: The main body is made of high-strength and durable ABS plastic. The bottom is equipped with high-quality PE soft rubber mats to prevent marks on the wall. Non-slip: The soft rubber pad is non-slip and clings to the wall to prevent the door from sliding. When your cute pet hits or the child shakes it, you don't have to worry about the door moving anymore. Multi-function: Child safety door bumper cups are used in many types of pressure type doors, such as: child gate, baby safety gate, baby gates, baby gates for stairs, pet gates with door, baby gate tensioners, child gates, shower tension rod, etc. The wall cups can be used for shower curtains with tensioned fixing rods.